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水分迁移是引起路基下土体冻胀的重要因素,目前国内外仍采用刚性孔隙来模拟水分迁移,这对承受荷载的土体并不适用。根据能量平衡与质量守恒原理,结合有效应力与孔隙率、体积含冰量与温度的关系,建立了压力作用下的考虑孔隙率变化的一维水热模型。基于改进的水分迁移试验装置,利用粉质粘土进行了开放系统下的水分迁移试验。研究结果表明:随着冻结时间的增长,补水量逐渐增大,导致冻胀过程经历缓慢变形、快速上升和下降3个阶段,荷载对最大冻胀速率的影响明显;最大含水率位置随着冻结锋面的下移而下移;随着荷载的逐渐增大,水分迁移量逐渐减小,开始补水的时间也推后。
Water migration is an important factor that causes soil frost heave under subgrade. At present, rigid pores are still used to simulate water migration at home and abroad, which is not suitable for soil under load. According to the principle of energy balance and mass conservation, a one-dimensional hydrothermal model considering the change of porosity under pressure is established based on the relationship between effective stress and porosity, volumetric ice content and temperature. Based on the improved moisture migration test device, the moisture migration test under open system was conducted using silty clay. The results show that with the increase of the freezing time, the water replenishment rate gradually increases, resulting in the process of the frost heaving process undergoing three stages of slow deformation, rapid ascent and descent. The influence of the load on the maximum frost heave rate is obvious. Front down and down; with the load gradually increased, gradually reduce the amount of water migration, began to replenish the time pushed back.